Norovirus is a highly contagious illness that causes the stomach and intestines to become inflamed. While it can occur anytime, 80 percent of norovirus outbreaks happen between November and April, according to the Centers for Disease Control and Prevention (CDC).

Last March, a new norovirus strain was identified in Australia. Named GII.4 Sydney, this emergent strain has since caused acute gastroenteritis outbreaks in a number of countries. In the United States, the new strain has spread rapidly nationwide, causing an increasing number of outbreaks, according to the CDC.Norovirus causes diarrhea, nausea, vomiting, and stomach pain, which can sometimes be severe. Symptoms can also include fever, headache and body aches.

"Sometimes you hear people say they have the stomach flu," said Mary Bowron, a registered nurse at Washington Hospital who oversees the infection control program. "There's really no such thing as stomach flu. Often what they have is norovirus."

According to the CDC, noroviruses are the most common cause of acute gastroenteritis and food-borne disease outbreaks in the U.S., causing about 21 million illnesses each year and 70,000 hospitalizations.

"It can be particularly troublesome for young children and the elderly," Bowron said. "Vomiting and diarrhea can lead to dehydration, which can be dangerous. If you get sick with norovirus, it's important to rehydrate yourself by drinking liquids as soon as you can keep something down. People who get too dehydrated may need medical treatment."

Spreads Easily

Bowren said norovirus outbreaks are often seen in situations where people have close contact with each other such as nursing homes, daycare, cruise ships, and classrooms. Nearly two-thirds of all norovirus outbreaks in the U.S. occur in long-term care facilities, according to the CDC.

The virus can be introduced into nursing homes or long-term care facilities by patients, staff, or visitors - who may not even have any symptoms - or in contaminated food. Outbreaks in these facilities can be long, sometimes lasting months.

"It spreads so easily from person to person, particularly when you are all living under one roof," she said. "The virus ends up on surfaces like counters, tabletops, and keyboards. You just need to touch any one of those surfaces and then touch your mouth."

While most outbreaks are caused by norovirus that has been spread from an infected person to others, it can also be spread by consuming contaminated food or water. Food can be contaminated when it is grown, shipped, handled, or prepared. Contamination by infected food handlers, such as those who prepare or serve food at restaurants or cafeterias, causes most norovirus infections, according to the CDC.

Wash Your Hands

There is no vaccine for the norovirus. The best way to prevent the spread of the disease is to wash your hands with soap and water, particularly after using the bathroom or changing diapers and before handling food. Other precautions include washing fruits and vegetables and being sure to thoroughly cook seafood.

"It's always good to have hand sanitizers around to stop the spread of germs, but they aren't as effective on norovirus," Bowren said. "You really need to use soap and water. It is the number one way to stop the spread of norovirus."

She said if anyone in the household does get sick, it's particularly important to practice proper hand hygiene. Laundry that is contaminated with vomit or feces from someone who is sick should be washed immediately, and anyone who is infected should not prepare or handle food for others in the household.

"Wash down surfaces with a bleach solution to reduce the chances of spreading the virus," she added. "The CDC recommends adding five to 25 tablespoons of bleach to one gallon of water."

Bowren said it's also important to stay home when you are sick with norovirus to avoid spreading it to others. Don't go to work and keep children home from school and daycare for at least three days after the symptoms disappear.

"You can still be contagious up to three days after you feel better," she added. "You can also be contagious before the symptoms start, but unfortunately there is usually no way of knowing you are infected."

For more information about norovirus, visit www.cdc.gov. To learn about upcoming Washington Hospital classes and seminars that can help you stay healthy, visit www.whhs.com.